High voltage expulsion fuse



ug. 28, 1934- J. vv. HUFFsTUTTl-:R

HIGH VOLTAGE EXPULSION FUSE Filed sept. 2o

Fig. i.

I. l l l 0.425,51?.

lNvENToR John I4( Haffszuzter.

ATTORNEY Patented Aug. 28, 1934 man VOLTAGE ExrULsIoN FUSE John w. Hummm, Forest mus, ra., assigner to Westinghouse Electric t Manufacturing Company, a corporation of Pennsylvania Application September 20, 1930, Serial No. 483,236

the ruse effectively extinsuishes arcs or both iow and high current values.A Y

Another object of my invention is to provide a fuse of the above-mentioned type with gas-` evolving plates that shall be decomposed by an arc to emit a gas that is turbulently passed through the arc stream.

A further object of my invention is to provide a fuse of the above-mentioned type with a casing within which plates of gasevolving material are disposed adjacent to a fusible element that may be distorted by the pressure developed by arcs of high current value. g

Heretofore, when a fuse of the expulsion type was selected for an electrical system, it was chosen of such capacity as to be capable of interrupting vthe maximum short-circuit current that-the system was capable vof developing. As such fuse devices could not be depended upon to interrupt arcs of low current value, considerable effort has been expended to develop a fuse that shall be capable of interrupting arcs of -all current values. If a fuse device is selected of such rating as to interruptores of low current value,4 the pressures developed when arcs of high current value-are established will disrupt the fuse structure.

In practicing my invention, I overcome the above mentioned difficulties by providing flexible,y gas-evolving plates within ,the fuse casing, about the fusible element. The plates fit snugly within the casing and are spaced apart a small y distance in order to provide a slot within which an arc is established. The slot thus formed is capable of confining arcs of low current value and of evolving suillcient iin-ionized gas from they plate material to effect arc extinguishment. When arcs of high current valves are established within the slot, the pressure developed thereby so distorts the flexible plates that the slot is increased in width an amount proportional to the amount of energy developed in the arc.

My invention will best be understood by referring to the -following specification, taken in conjunction with the accompanying drawing wherein: f

Figure l is a sectional view, in elevation. of a fuse device embodying my invention;

Fig. 2 is a sectional view of the structure illustrated in Fig. l, taken along the line II-I'I thereof, and

Fig.3isaviewsimilartoFig.2 with the ex- 13Claims. @L200- 121) ception that the fuse element is shown as having been interrupted and the plates distorted by the ensuing pressure.

My invention comprises, in general, a casing 1 having its upper end sealed by a terminal cap so 2 and its lower end provided with a clamping terminal 3. The upper end of the casing 1 is provided with a washer 4 having a central opening 5 through which a fusible element 6 extends and is held in fixed position against the top surface of the washer 4 by the cap 2 that is screwed upon the casing 1.

The clamping terminal 3 comprises a threaded ring 'I that is mounted on the outer surface of the casing 1 above its lower end. The lower surface o of the ring 7 is tapered to conform to the tapered surface 11 on the clamping annular member 12 that is provided with threads on its upper inner surface. A shallow slot 13 is provided in the, tapered portion of the ring 7 wherein the end of 75 the fuse element 6 is insertedand clamped by the annular member 12.

The surface of the washer 4, within the casing 1, is provided with an extension 14. A pair of insulating plates 15 are attached to the extension 80 14 by means of rivets 16. The plates are flexible and are made of gas-evolving material, such as fiber, that is decomposed in the presence of an arc to emit and un-ionized gas. y

The plates 15 are spaced apart a predetermined distance in order to provide a narrow slot within which the arc is conned and prevented from expanding laterally within the slots but is permitted to expand longitudinally therein. l

In the copending application of Joseph Slepian Serial No. 208,686 iiled July 27, 1927 and assigned to the assignee of the present invention, a. fuse structure is disclosed wherein the arc is extinguished by being confined ,within a slot between insulating side walls whereon the deionization oi' the arc stream occurs. The theory of arc extinguishment disclosed in the Slepian application is applicable to the present invention, and the connement of the arc by the side walls effects arc deionization on the surfaces thereof.

In addition to the yextinguishing eiect produced by the side walls, in close proximity to the arc, and in some cases'far greater than it in magnitude, deionization is effected by the gas evolved` 105 from the confining walls. In the copending ap-f plication of Joseph Slepian, Serial No. 423,660,l iiled Jan. 27, 1930 and assigned to the assignee of the presentl invention, an arc-extinguishing structure is disclosed wherein the decomposition 1.10

ensure suiicient evolution ci un-io more gas is evolved than is -nec assures that the arc will be .nbre plates may be resorted to in invention.

Aembodiment of my invention, it be a of the connng material is `passed turbulen through the arc stream.

My present invention takes advantage or additional deionizing eiect by having the plates 15 made of materials that readily decompose in the presence of an arc. The gas thus evolved is conilned between the plates l5 and is for tur bulently through the arc stream and, out of opening in the bottom of the mi.; t ionized gases are thereby deionized or blo trom within the casing and, upon the occurrence ci a current zero, in the course of its alternating cycle, the arc will be prevented from :wir reinitiated.

When my fuse device is employed in directa current circuits, the deionization of the are stream by the blast of gas :ur-11 from the decomposition of the material causes the arc voltage to be greatly increased. incre voltage causes the current to decrease, and with it, the rate of decomposition of material would ii the iiexible plates did not close down upon the arc as the current' .in ,1... a. By us closing down, the gas evolution is kept large., even though the current is reduced, and thus the are voltage is kept high. The width oi the slot r`e=l mains such as to have the arc voltage above the line voltage so that the cmu-w is con tinuously reduced to zero.

Fig. 2 discloses nbre plates l5 s sed on each side of the fuse element 6 in such er as to be wedged within the casing i to thereby prevent them from moving laterally away from each other. The plates are constructed to have su nre as to resist the pressurel developed by arcs of low current value, in order to retain the ares in intimate contact with the surfaces of the di. When heavy-current arcs are established betw the plates 15, the plates are distorted by the pres sure developed thereby, as shown in Fig. 3.; distortion is proportional to the amount of g@ evolved between the plates which is a function oi arc current. The distortion reduces the rate ci gas evolution and thus reduces the pre which would otherwise develop to a Lef-.t d. The reduction in gas evolution is vnot wir@ disadvantageous since, for the large currents, far

extinction. My device, therefore, es the ionized gas in an amount that is only 1v1.'- for the interruption of the c .l and there case of: low currents without exve 1- in the case of high currents.

It will be evident to those ed time that other expedients order to con ne the arc within a space 'wir "f in.

vent a too great increase of evolution increase in current. Various de for wi e dra materlal'frorn pro sin t@ the large currents will be evident to "zu the art, and all such are wi the and illustrated a 'While I have described additions, omissions and subsntuti made-therein without r -f from the spirit and scope of my invention, as set ro l companying claims.

I claim as my invention:

vdisposed within said slot.

v An expulsion fuse having a casing in the iorm of a round tube and a pair of substantially natgas-evolving plates mounted therein to proplates te' fdl their narrare closely spaced plates of gas-evolving material de tached from said casing except adjacent one point and mounted therein in such manner as to constitute a slot within which an arc is drawn and extinguished.

2. An expulsion fuse having a casing'and a pair of gas-evolving plates attached thereto at one point only and snugly mounted'therein in such manner as to constitute a slot,- and a fuseelcment' vide a slot the width or which may be increased by the pressure developed by an arc established between the plates.

d. 'An expulsion fuse having a casing and a 'nemble plate mounted therein and forming at least aportion of one wall of a passage wherein an arc is established, the eective cross-sectional area of said passage being materially variable due to the rlexure of said plate in such manner as to be a function of the pressure developed by thearc.' 5. A fuse device including a tubularcasing hav-4 ing two plates of gaa-evolving material extending' chordally tnereacross so as to constitute a slot within which anarc is dra and extinguished by the gas evolved from said gas-,evolving material. 6. An expulsion fuse having a casing and a 'pairj oi' exible gaseevolving platesmounted therein to providea slot the width ofv which may bernaterially increased by the pressure developed by' an arc established between the plates, the gasI evolved by the decomposition-of the plates being proportional to the currentpres'ent'in the arc. '7. In an arc extinguishingdevice, closelyspaced side walls comprising gas-evolving p latesthat are readily exed bythe pressure developed by an arc established between them.

B. In an are ext l.' forming a narrow.i slot for side walls being movable by being te increase thewidth ci the slot by the pe developed by thearc, the width to which the side walls are expanded being a function of arceurrent. f 9. In an arc extinguishing device, .side walls separated by a narrow slot forV co '-i- 1- an arc, the side -walls being movable to change their pe materially .to increase 'the width' ofthe 125 slot by the` pressure .developed by the arc, ,the width to which the. side walls 4are expanded being a function Vof arc energy, the said walls being de le in the presence of an arc to evolvejan; uri-ionized gas that passes ,turbulently through tlhecoedarc.'

, le. A fuse device inclu acasing having end 111.-.. t s 'at least one' oi which isclosedfor seal` ing the end of the casing, a plate of flexible ma: terial attached at only one portion 4to thejca'sina 135 a fusible element within the casing and extending al said exible plate for establishing 'anarc upon rupture thereof, thesaid arc' evolving a gas es. ,iny

t distorts said plate and passesgturbulently ughthearcstream li. Ina circxntinterrupter, means forca an arc', a ober closely co iizu. saidarc' laij. erally, said chamber. having a wallfoia which evolves an arcext .n 1.1.1; gas when. acteA Y ed upon by the are andwhichis ilegible permitting 145 expansion of said chamberto increase its crosse section ter in. a direction transverse' to thearc.- j f T l2. m a circuit interrupter, an elated 5' `for causing an arc in said chamber, said chamber therebetween, a fusible element `extending longii tudinally between said plates for causing an arc, said plates being of a material which decomposes when acted upon by the arc to give off a deionizing gas, and the cross-section of the space between said plates being variable in a material amount by said plates being bowed outwardly due to the pressure of said gas.

JOHNAW. HUFFSTUTTER. 

